D) gravel on the bottom of the aquarium. "Abiotic" means "non-living," so you would essentially pick the answer that does not include any organisms (the organisms here are plants, fish, and algae).
Answer:
the moon's gravity increases over the oceans and decreases over the land
Algae, Mosquito larva, Mallard Duck, and Racoon
Bladder, I believe. But they are saying that my answer must be 20 Characters long...
